Cam Timing Confirmation, I hope.

[bobswei]

I'm doing the cam timing and it's been a few years since I last did this. So, here we go. I have the crank Z1 at top dead center (seam in case). I rotate the cam, with the cam tool, clockwise (photo) till the valve starts to open up to approx. 0.1" or 2.6mm. 0.1" would be one rotation of the large needle on my domestic dial gage.?
I tighten down the large cam nut and rotate the crank clockwise, 2 revolutions, back to TDC. When I do this, the valve opens all the way then starts to close, back to 2.6mm at TDC. Is this correct? My memory seams to recall the valve just starting to open to the 2.6mm spec when the crank gets back to TDC.
Thanks for info.
Bob

[Flat6pac]

Bob, I'm lost at what you're doing, but it doesn't seem correct.
Crank at about 30 degrees before Z1.
Turn both cam shafts to the dot up, bring crank to Z1.
Pin both cams.
Dial gauge left side, rotate crank 360 degrees to Z1 and adjust left cam to spec by moving pin. For best reading with pin in, move left cam clockwise to move pressure against the pin. Lock nut on
Rotate 720 degrees and check your reading.
When your reading left cam, the right cam is off rocker. Move the dial gauge to right side and match the numbers of the left by rotating to the next Z1. The dots on the cam are now down because the cam moves at half rotation of the crank.
Reference, the difference by moving the pin to the next hole is approx. .15mm
Good luck, hope it helps.
Bruce

[al lkosmal]

Porsche 911 Cam Timing Adjustment and Setting | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article

regards,
al

[bobswei]

Bruce, I'm starting to find my way. Your instructions are starting to sound familiar from what I did in the past and forgot. I think, I was doing it right this time but not rotating the crank 360 to start out. Which would be why the valve wasn't moving like I expected. So, I think that means I was doing it wrong. But, I think I did it wrong before and when the engine was ready to fire up, it kept back firing. I rotated the rotor 180 degrees and solved the problem.
The part about "30 degrees before Z1" is a little confusing but with those instructions and the ones Al sent over, I think I'll get it fairly quickly.
Thanks, Bob

[Flat6pac]

The 30 degrees permits cam rotation without touching the Pistons as I completely build the heads, cams, and rockers, set valves before I install on the motor.
Makes it easier than rotating cams and moving the crank.
Bruce